If the effectiveness of teachers is to be improved, it is important for those who supervise teachers to be able to identify teacher behaviors which are related to improved student outcomes. The primary purposes of this study were to determine if supervisor ratings of teachers could be used to predict student achievement and to determine which teacher performance criteria are related to higher student achievement in fourth grade mathematics and reading and eighth grade Mathematics; Recent research efforts have identified many teacher behaviors that are related to improved pupil learning. This study assessed teachers on twenty-five observable criteria of teacher performance and sought to relate the performance criteria ratings to student achievement measured on both norm- and criterion-referenced tests. This study was a subproject of the Northwest Area Foundation School Improvement Model Project. Five school organizations participated in the study, and fifty-three teachers were involved. External, standardized norm-referenced tests and custom-designed, district-specific criterion-referenced tests were used to measure student achievement. The CRTs were designed by testing specialists at Iowa State University. Also, the project teachers were evaluated using the SIM (School Improvement Model) Teacher Performance Evaluation instrument. Individual teacher performance evaluation ratings and the achievement outcomes of their students were available for use in the present study. Teachers and administrators were taught how to do their jobs better; they were coached for better performance. Then, pupil learning was measured for any improvement. The study found that supervisor ratings on 21 of the 25 teacher performance criteria were related to improved student outcomes on criterion-referenced tests in fourth grade mathematics, fourth grade reading, or eighth grade Mathematics; Only one mean criterion rating was identified as related to student achievement on any of the norm-referenced measures. When the 25 performance criteria were clustered into four logical performance areas, the mean ratings in all four areas were related to criterion-referenced measures of student achievement in fourth and eighth grade mathematics, and mean ratings in two areas were related to improved student outcomes in fourth grade reading on criterion-referenced tests. No significant relations were identified with similar norm-referenced measures.